PPS Blog

A recently published perspective from Charareh Pourzand, Rex Tyrrell, co-editor-in-chief of PPS, and co-workers at the University of Bath gives an overview of recent findings on intracellular labile iron (LI) distribution and trafficking.  Using UVA radiation as an example, it also discusses mechanisms and consequences of oxidant-induced alterations in the intracellular pool of LI.  This perspective forms part of an upcoming themed issue on UVA.

Iron is a vital nutrient and is required for a wide variety of cellular processes due to its facile redox chemistry and affinity to oxygen.  However, when the redox-active chelatable ‘labile’ form exceeds the normal binding capacity of the cell this labile iron (LI) can become toxic.  In the presence of reactive oxygen species LI can catalyse the formation of oxygen-derived free radicals that overwhelm the cell’s antioxidant defence mechanism and result in cell damage.  Although intracellular iron homeostasis is tightly regulated acute exposure of skin cells to UVA induces an increase in intracellular LI and this appears to play a key role in the increased susceptibility of skin cells to UVA-mediated oxidative membrane damage and necrotic cell death.

To find out more follow the link below.  Full text is FREE until November 11^th.

Iron, oxidative stress and the example of solar ultraviolet A radiation
Asma Aroun, Julia Li Zhong, Rex M. Tyrrell and Charareh Pourzand
Photochem. Photobiol. Sci., 2012, DOI: 10.1039/C1PP05204G

New insights into mechanisms behind gender differences in skin cancer development are revealed in this article from Vivienne Reeve and co-workers from Sydney, Australia.  A contributing factor for skin cancer development in mice and humans is immunosuppression as a result of UVB light; whilst the contribution of UVA is controversial it has been shown to antagonise immunosuppression by UVB.  One of the mechanisms for this UVA protection which has been demonstrated in mice is mediated via oestrogen receptor-β signalling, suggesting a gender bias in photoimmune response to UVA.

Gender bias is tested in this study by comparing the UV-induced inflammatory and immune responses in male and female hairless mice. The study uses solar simulated radiation (SSUV) to induce sunburn, the resulting inflammatory oedema is measured through the increase in irradiated skinfold thickness and levels of the pro-inflammatory cytokine interleukin (IL)-6 in the epidermis.  Immune function was assessed by the contact hypersensitivity (CHS) reaction and its suppression by SSUV was related to the level of expression of the immunosuppressive cytokine IL-10 in the epidermis.

Results showed that although male mice had less intense sunburn with lower expression of IL-6 the CHS reaction was more severely suppressed by SSUV than females and this also correlated with increased epidermal expression of immunosuppressive IL-10. Exposure to UVB alone had equal effects in male and female mice, however, UVA irradiation induced immunoprotection in females but this effect was reduced or not present in males.  The results indicate that males have a relative unresponsiveness to the photoimmune protective effects of UVA.  This could explain the known gender bias in skin cancer development in both mice and humans.

Interested in knowing more?  Read the full article here.  Free until 4^th November.

Gender differences in UV-induced inflammation and immunosuppression in mice reveal male unresponsiveness to UVA radiation
Vivienne E. Reeve, Munif Allanson, Diane Domanski and Nicole Painter
Photochem. Photobiol. Sci., 2011, DOI: 10.1039/C1PP05224A